3,129 research outputs found

    A reusable rocket engine intelligen control

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    An intelligent control system for reusable space propulsion systems for future launch vehicles is described. The system description includes a framework for the design. The framework consists of an execution level with high-speed control and diagnostics, and a coordination level which marries expert system concepts with traditional control. A comparison is made between air breathing and rocket engine control concepts to assess the relative levels of development and to determine the applicability of air breathing control concepts to future reusable rocket engine systems

    System configuration and executive requirements specifications for reusable shuttle and space station/base

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    System configuration and executive requirements specifications for reusable shuttle and space station/bas

    On cost-effective reuse of components in the design of complex reconfigurable systems

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    Design strategies that benefit from the reuse of system components can reduce costs while maintaining or increasing dependability—we use the term dependability to tie together reliability and availability. D3H2 (aDaptive Dependable Design for systems with Homogeneous and Heterogeneous redundancies) is a methodology that supports the design of complex systems with a focus on reconfiguration and component reuse. D3H2 systematizes the identification of heterogeneous redundancies and optimizes the design of fault detection and reconfiguration mechanisms, by enabling the analysis of design alternatives with respect to dependability and cost. In this paper, we extend D3H2 for application to repairable systems. The method is extended with analysis capabilities allowing dependability assessment of complex reconfigurable systems. Analysed scenarios include time-dependencies between failure events and the corresponding reconfiguration actions. We demonstrate how D3H2 can support decisions about fault detection and reconfiguration that seek to improve dependability while reducing costs via application to a realistic railway case study

    Realising the open virtual commissioning of modular automation systems

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    To address the challenges in the automotive industry posed by the need to rapidly manufacture more product variants, and the resultant need for more adaptable production systems, radical changes are now required in the way in which such systems are developed and implemented. In this context, two enabling approaches for achieving more agile manufacturing, namely modular automation systems and virtual commissioning, are briefly reviewed in this contribution. Ongoing research conducted at Loughborough University which aims to provide a modular approach to automation systems design coupled with a virtual engineering toolset for the (re)configuration of such manufacturing automation systems is reported. The problems faced in the virtual commissioning of modular automation systems are outlined. AutomationML - an emerging neutral data format which has potential to address integration problems is discussed. The paper proposes and illustrates a collaborative framework in which AutomationML is adopted for the data exchange and data representation of related models to enable efficient open virtual prototype construction and virtual commissioning of modular automation systems. A case study is provided to show how to create the data model based on AutomationML for describing a modular automation system

    Shuttle Ground Operations Efficiencies/Technologies (SGOE/T) study. Volume 2: Ground Operations evaluation

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    The Ground Operations Evaluation describes the breath and depth of the various study elements selected as a result of an operational analysis conducted during the early part of the study. Analysis techniques used for the evaluation are described in detail. Elements selected for further evaluation are identified; the results of the analysis documented; and a follow-on course of action recommended. The background and rationale for developing recommendations for the current Shuttle or for future programs is presented

    Putting Teeth into Open Architectures: Infrastructure for Reducing the Need for Retesting

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    Proceedings Paper (for Acquisition Research Program)The Navy is currently implementing the open-architecture framework for developing joint interoperable systems that adapt and exploit open-system design principles and architectures. This raises concerns about how to practically achieve dependability in software-intensive systems with many possible configurations when: 1) the actual configuration of the system is subject to frequent and possibly rapid change, and 2) the environment of typical reusable subsystems is variable and unpredictable. Our preliminary investigations indicate that current methods for achieving dependability in open architectures are insufficient. Conventional methods for testing are suited for stovepipe systems and depend strongly on the assumptions that the environment of a typical system is fixed and known in detail to the quality-assurance team at test and evaluation time. This paper outlines new approaches to quality assurance and testing that are better suited for providing affordable reliability in open architectures, and explains some of the additional technical features that an Open Architecture must have in order to become a Dependable Open Architecture.Naval Postgraduate School Acquisition Research ProgramApproved for public release; distribution is unlimited

    Multi-level requirement model and its implementation for medical device

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    Indiana University-Purdue University Indianapolis (IUPUI)Requirements determine the expectations for a new or modified product. Requirements engineering involves defining, documentation and maintenance of requirements. The rapid improving of technologies and changing of market needs require a shorter time to market and more diversified products. As an important and complex task in product development, it is a huge work to develop new requirements for each new product from scratch. The reusability of requirements data becomes more and more important. However, with the current “copy and paste” approach, engineers have to go through the entire set of requirements (sometimes even more than one set of requirements) to identify the ones which need to be reused or updated. It takes a lot of time and highly relies on the engineers’ experiences. Software tools can only make it easier to capture and locate the requirements, but won’t be able to solve the problem of effective reuse of the existing requirement data. The overall goal of this research is to develop a new model to improve the management of requirements and make the reuse and reconfiguration of existing requirements and requirement models more efficient. Considering the requirements data as an important part of the knowledge body of companies, we followed the knowledge categorization method to classify requirements into groups, which were called levels in the study, based on their changing frequency. There are four levels, the regulatory level, the product line level, the product level and the project level. The regulatory level is the most stable level. Requirements in this level were derived from government and industry regulations. The product line level contains the common requirements for a group of products, the product line. The third level, product level, refers to the specific requirements of the product. And the fourth and most dynamic level, the project level, is about the specific configurations of a product for a project. We chose auto-injector as the application to implement the model, since it is a relatively simple product, but its requirements cover many different categories. There are three major steps in our research approach for the project. The first is to develop requirements and classify them for our model. The development of requirements adopts the goal-oriented model to analyze and SysML, a system modeling language, to build requirements model. And the second step is to build requirements template, connecting the solution of the problem to the information system, standalone requirements management tool or information platform. This step is to find a way to realize the multi-level model in an information system. The final step is to implement the model. We chose two software tools for the implementation, Microsoft Office Excel, a commonly used tool for generating requirements documents, and Siemens PLM suite, Teamcenter, a world leading PLM platform with a requirement module. The results in the study include an auto-injector requirement set, a workflow for using the multi-level model, two requirements templates for implementation of the model in two different software tools, and two automatically generated requirement reports. Our model helps to define the changed part of requirements after analysis of the product change. It could avoid the pitfalls of the current way in reusing requirements. Based on the results from this study, we can draw the following conclusions. A practical multi-level requirements management model can be used for a medical device—the auto-injector; and the model can be implemented into different software tools to support reuse of existing requirement data in creating requirement models for new product development projects. Furthermore, the workflow and guideline to support the application and maintenance of the requirement model can be successful developed and implemented. Requirement documents/reports can be automatically generated through the software tool by following the workflow. And according to our assessment, the multi-level model can improve the reusability of requirements
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